Fluxes for use in bonding plates of storage batteries to connecting straps

ABSTRACT

Fluxes for use in forming a bond between the lugs of the positive and negative plates, or grids, of a storage battery, and the terminal post-bearing connecting straps thereof, which, in their preferred form, comprise an aqueous suspension of an organic, substantially water-insoluble polycarboxylic acid such as adipic acid, and a water-soluble binder exemplified by polyvinylpyrrolidone.

United States Patent [191 Aronberg FLUXES FOR USE IN BONDING PLATES OFSTORAGE BATTERIES TO CONNECTING STRAPS [75] Inventor: Lester Aronberg,Chicago, Ill.

[73] Assignee: Lake Chemical Company, Chicago,

22 Filed: Mar. 27, 1972 21 Appl. No.: 238,609

[52] US. Cl. 148/23, 260/29.6 HN [51] Int. Cl. C23c 1/12 [58] Field ofSearch 148/23, 27; 260/29.6 l-lN,

260/29.6 TA, 29.6 WB; 106/181 Bergmeister et a1. 260/29.6 TA

[ Sept. 24, 1974 3,736,287 5/1973 Patella 260/29.6 TA 4,314,094 6/1968JA FOREIGN PATENTS OR APPLICATIONS 481,680 3/1952 Canada 148/23 708,9215/1965 Canada 148/23 719,889 7/1952 Great Britain 148/23 43-14094 6/1968Japan 148/23 Primary Examiner.l. Spencer Overholser AssistantExaminer-Ronald J. Shore Attorney, Agent, or Firm-Wallenstein,Spangenberg, Hattis & Strampel [5 7] ABSTRACT Fluxes for use in forminga bond between the lugs of the positive and negative plates, or grids,of a storage battery, and the terminal post-bearing connecting strapsthereof, which, in their preferred form, comprise an aqueous suspensionof an organic, substantially water-insoluble polyearboxylic acid such asadipic acid, and a water-soluble binder exemplified bypolyvinylpyrrolidone.

8 Claims, N0 Drawings FLUXES FOR USE IN BONDING PLATES OF STORAGEBATTERIES TO CONNECTING STRAPS This invention relates to fluxes for usein forming a bond between the lugs of the positive and negative plates,or grids, of a lead storage battery, and the terminal post-bearingconnecting straps of the battery.

In the assembly of the cells of a lead storage battery of the type usedin automotive vehicles, it is the practice to bond the lugs of theplates, or grids, which comprise the cells of the battery, to terminalpost-bearing connecting straps. The plates, or grids, and the connectingstraps are formed of lead alloyed with minor amounts, typically from 3to 6 percent of antimony, and it is important that the bond formedbetween the lugs of the plates, or grids, and the connecting straps bestrong, otherwise the operation and the useful life of the battery willbe adversely affected. Generally speaking, procedures used in attaininga bond require the use of heat to bring about a fusion of the metal ofthe lugs with the metal of the connecting straps. One such procedureinvolves preheating the lugs of the plates, or grids, to a temperatureof approximately 450F, and contacting the preheated lugs with the metalof the connecting straps which is held in a mold in a molten conditionat a temperature of approximately 925F. A flux is customarily applied tothe lugs prior to contacting them with the molten metal in theconnecting strap molds.

I-Ieretofore, fluxes such as zinc chloride and tin chloride, andmixtures thereof, which have been dissolved in water, with or without anacid, such as hydrochloric acid, have been used in forming a bondbetween the lugs and the molten metal of the connecting straps. Thesefluxes, however, have been found to be unsatisfactory due, in the main,to their corrosive properties and to their tendency to form oxides, theeffect of which is to weaken the bond between the lugs and theconnecting straps. These weakened bonds cause heating and resistance inthe cells of the battery, and materially shorten the useful life of thebattery. In an attempt to overcome the deleterious effects of thecorrosive zinc and tin chloride fluxes, it has been proposed to use asolution of an alcohol and rosin as a flux. However, such a flux, while.being non-corrosive, is unsatis factory for a variety of reasons.

In accordance with the present invention, fluxes have been evolved whicheliminate the disadvantages of fluxes heretofore used in connection withthe bonding of the lugs of plates, or grids, to the connecting straps ofstorage batteries. Apart from their non-corrosive properties, the fluxesof this invention are characterized by their ability to function at therelatively high temperatures utilized in'the bonding operation toprovide bonds between the lugs and the connecting straps which areuniformly strong. These objectives are achieved, moreover, without theconcomitant production of contaminants or pollutants, airborne orotherwise.

In brief the fluxes of the present invention, in their preferred form,comprise, as essential ingredients, an organic, substantiallywater-insoluble polycarboxylic acid, and a watersoluble binder. Inaccordance with an especially preferred practice of the invention, thefluxes are utilized in the form of aqueous dispersions or suspensions,the aqueous phase of the dispersion or suspension acting as a carrierfor the particles of the substantially water-insoluble polycarboxylicacid, and as the solubilizing agent for the binder. The termpolycarboxylic acid as used herein is intended to encompass acids having2, or more, preferably 2 to 4, car boxyl groups.

The organic polycarboxylic acids useful in the preparation of the fluxesof this invention, apart from being substantially water-insoluble, arecharacterized in that they will not sublime, or manifest no substantialsublimation, at the temperatures employed in bonding the lugs of batteryplates, or grids, to the connecting straps. As indicated hereinabove,these temperatures are of an order of 900F, more or less. Exemplary oforganic polycarboxylic acids which meet the aforementioned desiderataare aliphatic hydrocarbon dicarboxylic acids such as adipic acid andazelaic acid; aromatic dicarboxylic acids specific examples of which areuvitic acid, isouvitic acid, and homophthalic acid; aromaticpolycarboxylic acids exemplified by pyromellitic acid; and the like. Ofthe foregoing acids, adipic acid is outstandingly effective.

The binders having utility in the preparation of the fluxes can beselected from various water-soluble gums and resins. Exemplary thereofare water-soluble gums such as gum arabic, cedar gum and cebil gum;watersoluble gun-like compounds exemplified by sodium carboxymethylcelluloses; higher fatty acid partial esters of aliphatic water-solublepolyhydric alcohols or polyhydroxy substances; and water-solublepolymeric materials exemplified by polyvinylpyrrolidone, the latterbeing particularly preferred as a binder because it serves the addedfunction of improving the wetting, spreading and capillary action of thefluxes.

As indicated hereinabove, the fluxes of this invention advantageouslyare used in the form of aqueous dispersions or suspensions, thewater-insoluble organic polycarboxylic acid constituting the dispersedor suspended phase of the dispersion. The distribution of the acid inthe dispersion or suspension can be enhanced by reducing, as bygrinding, the size of the crystals or particles of the acid. Excellentresults can thus be attained with particles having a mesh size of theorder of about 40 to about 150, especially desirably about 90 to about120.

The quantity of the organic polycarboxylic acid and the binder used inthe preparation of the fluxes is somewhat variable. Typically, a flux,in the form of an aqueous dispersion or suspension, will contain fromabout 10 to 80 percent, usually about 40 to about percent, by weight, ofthe water-insoluble organic polycarboxylic acid, and from about 0.2 toabout 5 percent, especially desirably from about 0.5 to about 2 percent,by weight, of the binder. While tap water can be used to form thedispersions or suspensions, it is desirable to use distilled water forthis purpose, especially in those instances where undesirable chemicalsmay have been introduced into the tap water at, a water treatment plant,or by natural processes.

In utilizing the fluxes of the present invention, they areadvantageously applied to the lugs of the battery plates, or grids, atambient temperatures. The flux coated lugs are then subjected to apreheating operation, after which they are brought into contact with themolten metal of the connecting straps. The fluxes may be applied to thelugs in any convenient manner known to the art as by dipping, spraying,brushing, or the like.

While, as described hereinabove, the fluxes, in their preferred form,contain as essential ingredients, a waterinsoluble, organicpolycarboxylic acid and a watersoluble binder, in accordance withanother, but less preferred, aspect of the present invention, the bindercan be eliminated, and the polycarboxylic acid, in a dry, powdered orpulverulent form, can be used alone. When thusly used, the dry, powderedacid advantageously is applied, as by spraying from an aerosolcontainer, or the like, to the surface of the lugs, advantageously afterthe lugs have been preheated. In accordance with yet another, but also,less preferred aspect of the invention, an inert alcohol or ether can beused in place of water as a carrier for the polycarboxylic acid, with orwithout the binder. Specific examples of alcohols and ethers which canbe used, and which include higher boiling alcohols, are ethanol,isopropanol, hexanol, heptanol, glycerol, and the like, and higherboiling ethers exemplified by methyl cellosolve, ethyl cellosolve, butylcellosolve, and the like, and compatible mixtures thereof. In utilizingan alcohol or ether as a carrier, suitable steps should be taken to ventany vapors or fumes from the work area.

The following examples are illustrative of the fluxes of this invention.It will be understood that various other fluxes can be made in the lightof the guiding principles and teachings disclosed hereinabove. .Allparts are listed by weight.

EXAMPLE if Adipic acid (I mesh) 40 Binder (gum arabic) 0.5 Water 59.5

EXAMPLE 2:

Adipic acid (100 mesh) 40 Binder (PVP-polyvinylpyrrolidone) 0.5 Water595 EXAMPLE 3:

Azelaic acid (80 mesh) 60 Binder (PVP) 1 Water 39 EXAMPLE 4:

lsouvitic acid (100 mesh) 45 Binder (PVP) 2 Water 53 EXAMPLE 5:

Pyromellitic acid (40 mesh) 70 Binder (PVP) l jystq,

What is claimed is:

1. A water-based flux for use in forming a bond between the lugs of theplates of a lead storage battery and the connecting straps of saidplates, consisting essentially of an aqueous suspension of asubstantially water-insoluble polycarboxylic acid in particular form,and a water-soluble binder dissolved in the aqueous phase of thesuspension, the polycarboxylic acid being characterized in that it doesnot undergo any substantial sublimation at the temperatures at which thelugs of the plates of a lead storage battery are bonded to theconnecting straps.

2. A flux according to claim 1 wherein the polycarboxylic acid comprisesfrom about 10 percent to about percent, by weight, of the suspension.

3. A flux according to claim 1 wherein the polycar boxylic acidcomprises from about 40 percent to about 60 percent, by weight, of thesuspension 4. A water-based flux for use in forming a bond between thelugs of the plates of a lead storage battery and the connecting strapsof said plates, consisting essentially of an aqueous suspension ofadipic acid in particulate form, and a water-soluble binder dissolved inthe aqueous phase of the suspension, the adipic acid being characterizedin that it does not undergo any substantial sublimation at thetemperatures at which the lugs of the plates of a lead storage batteryare bonded to the connecting straps.

5. A water-based flux for use in forming a bond between the lugs of theplates of a lead storage battery and the connecting straps for saidplates, consisting essentially of an aqueous suspension of asubstantially water-insoluble polycarboxylic acid in particulate form,and polyvinylpyrrolidone dissolved in the aqueous phase of thesuspension, the polycarboxylic acid being characterized in that it doesnot undergo any substantial sublimation at the temperatures at which thelugs of the plates of a lead storage battery are bonded to theconnecting straps.

15.7; iliix accordiiigto claim fwliefehi the aqueous phase of thesuspension comprises from about percent to 20 percent, by weight, of thesuspension. fj flux according to claim 1 wherein the binder comprises,by weight, about 0.5 percent to about 2 percent of the suspension."'sfKfl'iix according to claim l wherein the particles of the acid havea mesh size of from about 40 to about 150.

2. A flux according to claim 1 wherein the polycarboxylic acid comprisesfrom about 10 percent to about 80 percent, by weight, of the suspension.3. A flux according to claim 1 wherein the polycarboxylic acid comprisesfrom about 40 percent to about 60 percent, by weight, of the suspension.4. A water-based flux for use in forming a bond between the lugs of theplates of a lead storage battery and the connecting straps of saidplates, consisting essentially of an aqueous suspension of adipic acidin particulate form, and a water-soluble binder dissolved in the aqueousphase of the suspension, the adipic acid being characterized in that itdoes not undergo any substantial sublimation at the temperatures atwhich the lugs of the plates of a lead storage battery are bonded to theconnecting straps.
 5. A water-based flux for use in forming a bondbetween the lugs of the plates of a lead storage battery and theconnecting straps for said plates, consisting essentially of an aqueoussuspension of a substantially water-insoluble polycarboxylic acid inparticulate form, and polyvinylpyrrolidone dissolved in the aqueousphase of the suspension, the polycarboxylic acid being characterized inthat it does not undergo any substantial sublimation at the temperaturesat which the lugs of the plates of a lead storage battery are bonded tothe connecting straps.
 6. A flux according to claim 1 wherein theaqueous phase of the suspension comprises from about 90 percent to 20percent, by weight, of the suspension.
 7. A flux according to claim 1wherein the binder comprises, by weight, about 0.5 percent to about 2percent of the suspension.
 8. A flux according to claim 1 wherein theparticles of the acid have a mesh size of from about 40 to about 150.